Automatic clutch



April 26, 1938; H. Nuff ET A'. :2,115,277

AUTOMATIC CLUTCH Filed Feb. 7, 1934 5 sheets-sheet 1 Tal /aroa Wal?. Ward/a? feea?.

Aprill 26, 1938. H. NUTT Er- AL .2,115,277

AUTQMATIC CLUTCH Filed Feb. v7, 1954 5 sheets-sheet 2 April 26, 1938. H. NUTT. E1' Al. 2,115,277

AUTOMATIC CLUTCH Filed Feb. '7, 1954 5 Sheets-Sheet 3 ZZ M zz Ef/Ez-Wm-*E' We fafa! Waff. df'af 7/ @ed 55 MLfl April 26,.l938. H. NUTT E-r AL i 2,115,277

AUTOMATIC CLUTCH Filed Feb. 7, 1954 5 sheets-sheet 4 f7.1/ E] EFE Warad' 72u a?.

AUTOMATIC CLUTCH Filed Feb. 7, 1934 5 Sheets-Sheet, 5

Pennac Apr. 26,1938

i PATENT OFFICE i AUTOMATIC cLU'rc'n nai-01a Nm and Hamid v. chicago, 111;,

assignors, by mesne assignments, to Borg-Warner Corporation, ChicagoJll.,v a corporation of Illinois r Appueauon February 7,1934, serial No. '110,046

1o claims. v(01. 19a- 105)` 'I'his invention relates to automatically operating clutches of the centrifugally energized type wherein the clutch is normally automatically -engaged and disengaged as the speed of the driv- 5 ing member is increased or decreased throughA a predetermined operating range. While the illustrated embodiments of this invention have been designed to meet the specific operating requirements of 'automotive clutches where the clutch is disengaged -at idling; speeds and engages as the engine is accelerated, it will be understoodY that the clutch of our invention can be usedfor various otherpurposes. I

It is an object of this invention to provide an x5 improved clutch of vthe class described 'that will smoothly pick up the load on the driven member vwithout shock due toslack or play inthe driven connections even at extreme rates of acceleration of the driving. member or engine.

o Heretofore centrifugally energized clutches have tended to be rather harsh or sudden in action at high rates of acceleration of the driving member because of the nature of the centrifugal force actingon the weights which operate the clutch- 2- pressure plate. Since theweights must swing outward from the clutch'axis to respond to centrifugal force the `first slight outward movement of the weights, as centrifugal force increases to a point sufficient to overcome the retractive force provided for. the weights, serves to increase the centrifugal arm or radius of the weights with an increased centrifugal effect thereon that -builds vf up' further energy as the weights swing furtherI out, the net result being thatthe weights act 315 quite suddenly when oncek displaced from their inactive position. Since backlash or clearance is provided in a number of places in the driven connections, which clearance is cumulative, such a. rapid engagement of the clutch will pick up 4o these clearances successively to deliver quite a shock'to the mechanism when the accumulated clearance is taken up suddenly. Thisdescription `is equally applicable to other forms of centrifugally controlled clutches vbesides that disclosed herein, and the present invention relates to the provision of an auxiliary or first stagel clutch engaging mechanism. operating independently of and in addition to the main clutch mech-V vide an improved and simplified multi-stage cen-y trifugal clutch operating mechanismwherein the ilrst stage weights are much smaller than those of the iinal stages and exert only enough torque on the driven disc prior to the engagement of the iinal ,stages to take up drive line backlash, the iirst` stage weights operating independently of the main pressure plate so that they do not have to operate the latter, which can thus be arranged to be retracted by reasonably'heavy springs to assure holding the pressure plate in its released position without danger of clutch drag due to incomplete release below al predetermined `speed upon retraction of the centrifugal weights acting thereon. i

Y It is another object oi this invention to provide -animproved and simplified4 two stage centrifugal clutch wherein the first stage operates directly against-the driven disc and independently of the usual pressure plate, which plate is operated by the second stage,

Other and further important objects of this invention will lbe apparent from the disclosures in the specification and the accompanying drawings.

trated in the' drawings and hereinafter more nmydescribed. i. On the drawings:

` Figure 1 is a central longitudinal section4 on the line I-I of Figure 6, with partsin elevation,

showing an automaticA clutchy embodying `one form of the present invention, the clutch being v shown in'itsV disengaged position. f 1 p Figure 2 is a fragmentarysectionsimilar toy than that required to produce'iirst stage engagement. 1

Figure 5 is a fragmentary-section on, the line V-V of Figure 6 showing one group of the clutch pressure springs.v

Figure 6 is a rear view of the clutchwith the I driven shaft anddiscl omitted; the housing being partly broken away to show some of the structure in section and elevation. Q 1' Figure 'i is a fragmentaryv section similar `to vthat of Figure 2 showing another form of Vfirst stage mechanism in its disengaged position.'-

This invention. (in a reierredfform) isfillusused,"su ch`fr exampleas are illustratedin vari- Figure 8 is a section similar-to Figure I showing the first stage mechanism energizediby cenv`trifugal force. Y

Figure 9 is a fragmentary rear elevation ofl Figures 'l and with the housing broken away.

' Figure 10 is a vsection .on the line X.-X of Figure 9 showingthe vflr'st stage retractor spring.

As shown: f

The present invention relatesto the provision ,o of a first stage clutch engaging mechanisml intended to takerup back-lashin thedrivenjr train of shafts and gears and whichilrst stage mech-l vanlsin'can be used with various types ofsecond-f- *Y ary or power engaging'mechanism ythat provides i substantially all of the torque producing engaging pressure V when a load is being transmitted through the clutch. llor"r this reason the illus- Vtrated form of second stage mechanism is not essential to the present invention as other forms of centrlfugally energized ,mechanism can be ous'prlor joint orj soleapplications of ours.r

It willbe convenient to rst 'describe' the'forn'i.V of automatic clutch chosen to illustrate the appli' "cation of-the ilrststage mechanisms' of this in- .-vention. To .this end reference may'r'st bel had Y' 1 The'fsecond stage mechanismcomprisesaconventional-drive'n discV il carrying' friction facingsf. Ii'y and mounted on a hub lI2 through a torque lcushioningA drive including springs il. f Inv order v*to increase the smoothness fof engagement', thej disc vIl'risslotted and distortedin lthe region off 5 the friction facing's il', which latter areA individually-attached to thev disc in su'cha'way as tobe somewhatspread apartwhen disengaged but v compressedby the vengagement of the clutch, asy

willbeevidentfrom a comparison voi' Figures 3 I and'4.- As far asthe clutch rnechanisrnis con-. cemed this structure'merely calls 'for an increase inthe running clearance orrahge of movement ofi i the'Y automatic andmanuali',cor'itrols.A The 'f disc ving cups being located betweenthevring and il is disposed betweenlthe rear .face of the engine V- flywheel i4 and (an axially movable pressure plate il, which plate is advancedl toward the flywheel to takeuprunningclearances and'atten out the distortions inthe viiscv in thus mppingthe fries tion-facings and disc'betw'een the flywheel and press'urerplate to transmit powerffroni'fthe` fly-A -wheeifto the disc lean-dits vhun iz to la .driven shaft il r.which may form the driving'ishaft Lof a f. transmission I1.' The front endf of theshaftli Y is preferably Isupported in,a pilotv bearing il in wheelV i4.- =The pressure Vplate and other/'rotating.- membersv are contain'ei'i within a housing l20 boltedto the flywheelgand the pressurev plate is constrained r to lrevolve with .the ilywheel by lugs* 2| engaging slots 22'fin the-,housing 2li. 1 l

'Ihepressureplate is backed byga'sprin'g mount-r i ing ring122, double pressure springs 24 in rcentervrtheho'using,as shown in Figure 5.' 'Ihese springs )are preloaded to a-total pressure determined by the, desired torque rating ofthe clutch,v and are. l equivalent'to the pressure springs oi' a normal evident to the` then serve'to take up clutch in thatthey determine the maximum engaging pressure which is transferred from the spring ring to the pressure plate when the several weights 26 swing outwardly yinto contact with' the flange 21 of the spring ring, as shown in VFigure 4. ,The spring ring is normallyoheld vin theclutch ydisengaged position of lF'lgures'l vand 3 by throwout flngersjl fulcrumed at 29 to an anchor stud 30 adjustably secured in the hous- V ing, the outer ends of the' flngers'having a linkV 3il connecting to the spring mounting ring, while the inner ends'of the flngers'normally contact` 'Y and followathrowout bearing I2 siidable upon g a'sleeve' .enveloping the driven shaftgil. i

' The'throwout bearing is backed byra throwout fork 33 on a shaft 3i operableby aconventional clutch pedal (not shown), and when thebearingis held in its midposition of the illustrations.

it actsy through the :multiplying leverage of the f ngers Zl-to hold the spring ringretracted against thexloadeofv the precompressedpressure springs. v f v By shifting the throwoutfbearing to Vthe-right,-

whenfthe-,clutch is disengaged, the spring-ring is I ipermittedto move to the left to'cause clutch enjgagernent at ga time whenV the automatic :mecha- Anismwould otherwise hold the clutchdisengaged. By4 shifting: the throwoutabearing fto *the left,

when rthe clutcheis automatically engaged,v the,l bearingacts throughthe lingers 28 to retract the` spring ring andA pressurey plate,v thus disengaging ,v the clutch. The throwoutfbearing is normallY located at its neutral position shown by'positive f positioning-mechanism notshown in the drawings, o

'Ihe pressure plate, when f the; centrifugal ing` ring by retractor springs 25 onshouldered guide studs afcarried kby the pressure ifplate,

butthe operatQr-.has complete control over the clutch andcan manuallyrelease or'engage it at will, irrespective of theaction of theautomatic y control. y 1

thus vholding-the pressure plate in its disengaged' position yunder suchl circumstances. The -automatic oripentrifugal engagement of the clutch i s accomplished bythe' routwardQswinguof `'the vweights -26 which ycarry oiset lugs 36 interposedv between thev pressure plate and springfring;r

passing throughslots in the latter'. o iresemble'rboots, the heels fulcrumslforith'e weights, bearing againstA hiirii-v pressure plate; while the f I 31 of 1 which form enedv inserts, on the toes-I9, engagebeneath the springy ring. Aghard# ened wearplatefil may belnserted between the 'i toes and thespring ring rto take -Vthe sliding'fric.- f .tion,at-this point. o

Anoutward movement 'of the, weights .2,*in;f Y response to `increased oentrifugalfforce, 'causes' themes n to pivot 'about the heels u romy-nie pressure plate and spring ring apart, compressing vthe. retractonsprings-. 3 Since thespringring. yis located bythe lingers the eifect is to advance the pressure platefto the left intoelutching''Ken-k gagement withthe -Ydriv'en-.disc..n When thedisc distortion `and running clearances have z been'k takenrup,the-flnalmovement of the' weights 2l..

into contact, with the springpring flange 21 serves The 1 lugs 'c to move` they spring.VV ring slightly. tok the right;r l transferring the pressure spring, loadrto the lpxes-` surejplate and atthe, saine time iivithdrinvingV the throwout fingers from contact with thev thijowout beaxingfasshown in Figure 4. Light springs li;

-outflngerlinkage` Y v Y, L The first stagemechanism of the present inven'-A 'il any looseness in the thro'w- M.; the first stage weights or backlash take up.

being designed to operate at an intermediate speed slightly below 65o R. P. mi.' r to allowrolrv a.

higher idling speed for starting and warming up a cold engine. It is to be noted that the specific speedsmentioned are not essential and are completely under the designers control to meet vary-` ing requirements by a suitable selection of weights, leverage and retractor spring strength.

The first stage mechanism shown in Figures 1 and.2 comprises a number of small weights 42 mounted on one end of levers 43 each fulcrurned on the edge of ra slot 44 in the spring ring, the v other end of the levers ibeing bent to clear the v periphery of the pressure plate and terminating in a toe 46 which is curled or `dishedsomewhat to prevent the edges thereofY fromdigging into the friction facing `Il when the weight and lever swings `to bring the toe 45 into engagement with the driven disc. The first stage weights are much smaller than the second stage weights 26 and are capable of exerting only enough torque on the driven disc to take up the driven line back.

lash. The first stage weights therefore have only a very limited power and donot affect the pressure plate at all. A close comparison of Figures land 2 will show that thev weights `42 only partially flatten out the distorted segments of the driven disc. n its retracted position of Figure 1 by a retractor stud 46 and spring 41 which spring is designed to allow the weight 42 to respond to centrifugal force at a lower rotative speed than that required vto energize the second stageweights.

The above described form of first stage weights has the advantages of simplicity and economy,A

. but the several weights act independentlyA and therefore must be synchronlzed,and the friction surfaces 46 of the levers are intermittent so that there is a,l possibility of injury to the friction fac- The second form of first stage mechaing Il. nlsm, as shown in Figures 'l to l0, overcomes these drawbacks. In this form of the invention the first stage weights 46 are carried by levers 41 fulcrumed at 48 in a notch on the inner edge of the spring ring, and the levers engage pins 46 on a small pressure ring 50 instead of bearing directly against the friction facing. 'I'he small pressure ring 56 is normally held retracted by springs 6|. 'I'he second form of this invention does not differ in principle or function from that iirst described, and is an improvement thereover in that a continuous friction surface is provided, and the several 'weights are constrained to operate in unison.

In the operation of the automatic vclutch of this invention, it will be understood that the second stage mechanismformsa completelyV operative clutch intended toacarry.substantially the whole load, the first stage mechanisrmbeing ina sense an auxiliary clutch engagingmecha-y nism more sensitive than theloa'd carryingmech'- lanislix and independent yoi! the relativelyv massive.

pressure plate thereof. vBy making the first stage independent of the pressure 1plate,it can be made so muchless powerful tha'tits onlyjappreciable effect is to take up thebacklash in`-thedriven` train prior to the driving engagement ofthemain j clutch, and to thus avoid the possibility;foiff'shock.`

Each weight 42 is normally held in of the disc relative to its hub. `The cumulative backlash in the driven train sums up to an easily appreciable slack sumcient to develop a substantial shock'- if taken up suddenly under load,r as

it includes the spline clearances in the hub of the driven disc, the transmission'and the`rear axle.

and the various gear clearances in the Atransmission and rear axle, which 'may individually be small, butvrapidly mount dueto the number of clearance spaces, whichLall increase with wear.

AAssuming that the engine is disconnected from the transmission, and is idlingunder normal conditions, an increase in enginespeed slightly above the usual fast idle provided for warming up will serve to energize the rst stage or auxiliary clutch weights, swinging them` outwardly. into contact with the spring ring against the Vresistance of' the first stage retractor springs. This results in the lever ends 45 or the small ring 50 being brought into contact with the driven disc with Vsuflcient force to take up the running clearance'between the disc and the flywheel, thusk setting up a drag sufdcient to take up the backlash in the driven connection before the engine can be accelerated to a higher speed to bring the second stage'or main clutch mechanism intov play to advance the pressureplate into full driving engagement with the driven disc. Even though the engine be acceleratcd as rapidlylas possible from its idling speed, the I first stag-ev or auxiliary clutch l will function suillcientlygin advance` of the` main clutch to take up backlash in the driven connections and thus prevent the production of a shock yhat would ordinarily be unpleasantly noticeable to the vehicle occupants.r

' We are aware that many changes may bemade and numerous details of construction may be varied throughV a wide range without departing from the principles of this invention, and we therefore do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art.

We claim as our invention:

l. In combination with acentrifugally energized clutch mechanismengageable at a. predetermined rotative speed including driving and driven members and a pressure plate for clamping the driven member against the driving member, an auxiliary vcentriiugally energized mechanism operable at a lower speed than th^ first mentioned clutch mechanism, and independent of the pressure plate thereof, -for providing light preliminary engagement between said driving and driven members to take up backlash in the driven connections prior to the engagement of said clutch. y

2. In combination with a centrifugally energized clutch mechanism engageable at a predetermined rotative speed` including driving and driven members and a pressure plate for clamping the driven member against the driving member,

auxiliary clutch engaging means independent of said pressure plate and automatically operable to lengage the driven memberat a lower speed than said clutch, whereby to provide -a light preliminary engagement prior to the full engagemen of said clutch.

t`32 The combination with a centrifugally energizable clutch engaging mechanism including driving and `driven members, a pressure plate,

and centrifugalweights for advancing said pressurc plate into clutching engagement with said 7oKL driven member, of an auxiliary clutch engaging mechanismcomprising a pressuremeans in V allel with but independent `ofgsaidpressure operable in response to centrifugal force to pro'- vvide alight preliminary engagement'between said`` drivinsrand v"driven members.kk

4..The ycombination with a. centrifugally en- I `rergizable, clutch en 5. The combination with av centrifugally energizable Y. clutch engagingv mechanism `including (driving and driven members, a pressure plate, L and centrifugal weights for advancing said pres- 1 -sure plate into ciutchingfengageme'nt with said driven memberof an auxiliary clutch engagingvr mechanism comprising independently operable elements acting, when under the influence of cen'- trifugal force acting thereupon, directly against the driven member to produce a drag thereon suf" i lficient totake up'backlash in thefdriven connec-` driving and driven members-a pressure plate, and centrifugal weights for advancingsaid pressure i tions.

ergizable clutch engaging mechanism including yplate into clutching vengagement with said driven nism comprising a second independentlyno! the V'nrst mentioned pressure plate, and centrifugallyV energized meansffor advancing said second plateinto contact with themember, of an auxiliary clutch engaging mechapressure plateoperable driven member lprior to the'fengag'ementthereof bythe first mentioned pressure plate.r

7. Iny a clutch including/driving -anddriven members and aV pressure plate controlled by centrifugally energized means for engaging A.said members through they pressure plate to transmit the'load above a predetermined rotative speed of the driving member, and centrifugally operated means independent of said pressure plate for inioperation of the pressure plate. y

`tially engaging'the driven member prior to they par; P19479 gaging mechanism including driving anddrive'n members-.a pressurejplate, and*1-` centrifugal weights 'for advancing said pressure"- plate into; clutching engagement 'withsaid driven member, of kan auxiliary clutch engagingy mecha# nism independent'of-said pressure plate and cenf trifugally ,energizable in advance of the first men# .tioned clutch vengaging 'mechanism to cause pre- Y .liminar'y engagement between `the driving and driven members;y l

A plate.

member Y vsaid pressure n s i crease in-speed of said driving-memberabove a plate vandmountirig ring s thus to establish frictlonalengagement"between establish a frictional 6. The combination with 'a rcentrifugally er1-Y [am a friction eiuteh including drivingand driven members and av pressure `plate carried by.,

for` engaging thefdriven said driving'y member member, centrifu'gally controlled mechanism'hav-l iluence of centrifugal Aing-a ',ierma'nentfdrive connectionrwith saiddrivf -ing member for operating said pressure plate and lauxiliary `mechanism actingrwhen under the inforce', directly jagain'st the 1 driven member forinitiallyengagingy thedriven member prior to the 9. In ian automotive vehicle clutch, the combinatian with a' dnving'assembiy iniudinga drive ing member,v a pressure platea spring mounte". ing ring backing said pressure plate, ofaa ldriven. adapted to be frictionallv enga'gedfbyl plate, means responslvefto an inf predetemlllled R. P, tospread saldi,

aprt from yoney -another pressure plate land 'drivenrmemberr and v.ineens carried by said mounting ringzand operative in responsev to rotation of'said drivingl member atv a speed less thany said driving connection between said mounting ring and said driven member independently of'said pressure plate.

f 10. In an automotive: vehicle clutch,a[driv. l ing assemblyincluding a pressureplate, ajd'riven y member having `a friction vfacingv adapted tofbe frictionally engaged by said pressure plate, means kcarried bysaid driving assemlzplyiand.responsive,v

to' an increase'in` speed thereof beyonda prede'- terminedR. -P. M;

en vmember,v andi-means, including Va pressure member. responsive to rotation fof' said drivingasisembly at a less `thany said predetermined VR. P. M. to causefrictional engagementbetv'veen--'V said pressure member and said ,frictionk facing onY said driven' member independently of the I oppredeterminedA R. 5P.' M. to

to surge "said *pressure plate A' Minto frictional driving engagement `with the div` eration of said pressureplategsaid 'iastnamed y means being so arranged relative to saidfirst. l Vnamed vmeans as to be'rend'ered inol'aseratiyer dur- I ing the'operation of said first named means when urging the pressure plate inengagement the driven member. Y s Y p HAROLD NU'rr.

HAROLD. 5 

